I tend to believe that the best interfaces have already been made. Behaviourally, CDE is the best and most consistent interface ever made. It looked like ass, but it always did exactly as you told it to, and it never did anything unexpected. When it comes to looks, however, the gold standard comes from an entirely different corner - Apple's Platinum and QNX' PhotonUI. Between all the transparency, flat-because-it's-hip, and stitched leather violence of the past few years, one specific KDE theme stood alone in bringing the best of '90s UI design into the 21st century, and updating it to give everything else a run for its money. This is an ode to Christoph Feck's Skulpture.

I compile the git version from time to time to no avail, running KDE 4.8.4 the Skulpture theme does not even appear in the list to be selected.
So in the mean time I switched to QtCurve, one can configure it to look pretty much like Skulpture and as a bonus all the GTK+ apps look uniform too.